Carriage translating mechanism



y 1948. c. H. RICHARDSON CARRIAGE TRANSLATING MECHANISM Filed Feb. 28, 1944 2 Sheets-Sheet 1 INVENTOR 62/4/9155 f1. fi/a/MRosoA/ Illllllllllllll Ell! III May 11, 1948. c. H. RICHARDSON 2,441,153

CARRIAGE TRANSLATING MECHANISM Filed Feb. 28, 1944 2 Sheets-Sheet 2 5 I 67 I 5 i 65 5 i l i 7% 2:9 E I I i 2'9 f k '55 Y II, I, lf 5 6466 @629 E 5 66 & 55 36 Q Fig. 1/. 1 1: m. 72' 84 75 7/ a Patented May 11, 1948 UNITED STATES 2,441,168 I CARRIAGE TRANSLATIN G MECHANISM Charles H. 'Richardson, Great Neck, N. Y., as-

signor to The Sperry Corporation,

tion of Delaware a corpora Application February 28, 1944, Serial No. 524,306

16-Claims. (01. 74-4243) This invention relates, generally, to carriage translating mechanisms and particularly concerns apparatus for translating thecarriage of a precision instrument by a lead screw and nut arrangement.

A major object of the invention is to reduce backlash between the lead screw and'the carriage of a carriage translating mechanism.

Another object of the invention is to provide a carriage translating mechanism in which a lead screw serves as a rail to upport the weight of the carriage. I i

A further object of the invention is to provide an anti-friction rolling contact between a'translat'able carriage and a lead screw for causing translatory motion of the carriage.

A still further object'of the invention is to eliminate back-lash in an anti-friction carriage translating mechanism by providing a springpressed rolling contact element for engaging the 20 thread of a lead screw.

Other objects and advantages of the invention will become apparent from the following speci fication-taken in connection with the accompanying drawings wherein:

Fig. 1 is an elevation view partially in section of a variable-speed device having a carriage translating mechanism embodying the invention; Fig. 2 is a vertical section of the variable speed device shown in Fig. l; I v

Fig. 3 is an enlarged rear elevation view of the carriage translating mechanism shownin Figs. 1 and 2;

Fig. 4 is an enlarged bottom view of the carriage translating mechanism shown in Fig. 3;

Fig. 5 is an end view partially in section of the carriage translating mechanism shown in'Fig. 3; Fig. 6 is a plan view of the carriage translating mechanism as seen from the top of Fig. 5;

Fig. 7 is an enlarged section of the lead screw 40 showing a wheel on the carriage in engagement with the thread of the screw; Fig. 8 is an elevation view of variable speed device having a modified form of a carriage 45 translating mechanism;

device shown in Fig. 8; Fig. 10 is an enlarged elevation view of the care riage translating mechanism. shown in Fig. 8;

Fig. 11 is a similar view with portions of the sleeve broken away for purposes of-clearness;

Fig. 12 is an end view of'the carriage translation mechanism shown. in Fig. 10 with parts broken away for purposes of clearness;

Fig. 9 is a vertical section of the variable-speed I pair of balls 26 and 2'! 50 presents a substantially smooth,

According to the invention a trapezoidal lead screw is rotatable about an axis and a carriage 10 has a, sleeve surrounding thescrew and supported thereon by anti-friction elements including a rotatable member engaging the thread of the lead screw to translate the carriage along said axis. Spring pressure is appliedto the anti- 1 friction elements to reduce play and eliminate back-lash between the carriage and the lead screw. A guide rail is ngaged by an velement on the carriage to prevent therotation thereof about the screw. t

In the form of the invention shown in Fig. 1, a conventional variable speed device having a casing 2i supports a disc 22, rotatable on bearings 23 and adapted to be drivenby a shaft M. A carriage designated, generally, at 25 carries a for transmitting motion from the disc 22 to anoutput cylinder 28. Suitable rollers 29, 29 and guide buttons 3t, it may be interposed in the carriage for retaining the balls in alignment. One part 33 is pivoted to the casing 25 as by hinge (i l and is spring-pressed ing the ball carriage 25 together with the balls 26 and 271 radially of the disc 22 along the axis of rotation of the output cylinder 28. For this purpose a lead screw it is journaled in the casing 2i for rotation about an axis extending parallel to the axis of rotation of the output cylinder 28. The ball carriage 25 is supported on the trapezoidal lead screw M by a plurality 'of rollers 52, it, it and d5, arranged in pairs, as shown in Fig. 6, on opposite sides of the carriage 25 and spaced onithe same side of the periphery of the lead screw 45. The rollers are arranged to span the cylindrical surfaces of Y adjacent screw threads, so that mutual rolling contact is pro vided therebetween, and the surface of screw it cylindrical, frictionless bearing surface for the rollers.

As shown in Figs. 2, 3 and 5, rotatable memher, in the form of wheel 41, is carried by a shaft 68 journ'aled in a bracket 49, which is pivoted,

as by pin 5t, to-the'main bodyof the ball carriage 25. The axis o! the shaft "4 axis of rotation of the wheel [his that passes through the. contact. point".

and is preferably atvan: angle to axis 48 of the screw corresponding 1 tinuously pressing with the sides oi thread 58 ported on the screw in engagement with the crest manner enables the lead a plane of the wheel 41 ,0! :two parts, as shown in the drawings. The

to helix angle (a) oi'thre'ad", asfshown most clearly in Fig. 4. V l

1 A bolt 53 projects through the carriage 2i and a lip 54 on the bracket to hold a compression spring 55 which acts to pull the bracket 48 toward-the body or the carriage 28therebyconas shownin Fig. 7. v By this construction, the carriage 25' is surl- 4-| by the wheels 42, 4 8, 44 and 45 that are held of thread 59 by spring pressure exerted between thecarriage 25 and thebracket 48 which acts as a lever to. maintainthe wheel." in engagement with the sides of the thread 58. As shown in the drawings the supporting wheels 42, are arranged to act on one side of the screw 4|,

the opposite, side. The pressure spring it thereby holds the supporting rollersin engagement with the truncated crest or the'thread as, well as the wheel 41 in engagement with the sides of the thread. fl

The provision 01 a rolling contact element for engaging the thread of screw to act as a. rail for supporting the carriage as well as translating-it. Translation of the carriage is effected by rotation orthe lead screw 4|. .The supporting rollers and the wheel 41 are in rolling contact with the lead thewheel 41 into engagement of the lead screw 4| ,f

the lead screw in this xr mber 68, which is shown in detail in Figs; to inclusive. consists 'oitwo parts 1| and-l2 having innerdiameters suitable for sur rounding the screw 88.v The sleeveparts H and 12Jare each formed with helically-shapedend surfaces 12 and 14, respectively, having beveled inner portions 'IS'and 16 which when placed together cooperatetoiorm a'heiically-shaped groove or cage 01' a slightly larger: diameter than the inner d iarneter'oi the sleeve parts" and 12. The ends 48, 44 and-48 I of the helically-shaped beveled portions 15 and- 18 ofthe end surfaces 13 and 14 are bridged or 1 Joined by arched portions 18 and .18, which, as

shown most clearly in Figs. 10, 14, and 15, extend outwardly from the center or the sleeve, a distanceat least equal to the root diameter of when the two surfaces I8 and 14 of the sleeve part II and I2 face each other they form a continuous helicoidal groove providing a helical shaped track for almost a complete revolution and connected by arched portion 18 and 19. whereas, the wheel 41 engages the screw 4| on a to engage the thread (Figs. 11 and 15) of the screw 4|, s0 rotation of the screw causesthese or the thread 68, itiollows the v through shaft 48 andbracket.

49 to translate the carriage 25 along the axis oi rotation of the screw 4|.

In order to prevent rotation of the screw from causing rotation of the carriage at about the axis of rotation of the screw, a guide roller "and a cooperating flange 84, carried by anarm 82, de-

pending from the carriage 25, engages a guide rail 83, which runs parallel to the axis of rotation of the lead screw 4|. v

Arrangement of the supporting rollers on the truncated crest of the screw, as noted, and the rotatable element in engagement with the thread of the screw provides an anti-friction support for theball carriage on the screw. "In addition the spring pressure it continuously inengagement with the sides of thread 59 to eliminate back-lash orplay between the screw 4| and the carriage 25. A modified form of the invention is shown for translating a ball carriage 65 in Fig. 8 which corresponds to the ball carriage 25 shown in Fig. 1. Other parts ofthe variable speed device, shown in Fig. 8, are designated by reference numbers corresponding to those shown in Fig. 1.

As shown in Fig. 8, carriage 85 is supported by two sleeve members 86 and 81 which are identical and include rotatable elements coupling the sleeve members 86 and 81 to lead screw 88 for supporting the carriage G5 on the lead screw and causing translation of the carriage upon rotation oi the lead screw. The lead screw 68 is iournaled in the casing 2| for rotation about an axis to the desired direction of translation oi the carriage 65 in moving radially of rotating disc 22.

Each of the sleeve members 88 and 81 consists leadscrew 88 and are retained in position by the v helicoidal groove formed by end portions 13 and 14. The helical pitch of the end portions is the same as the pitch of the thread 83.

t A- plurality of bolts 84, 84 extend through the two sleeve parts H and I2 and carry compression springs 85 which continuously exert pressure on the two parts. In this manner the beveled portions of the end surfaces 1| and 12 are caused to form a continuous groove acting to press the balls 8| into engagement with the sides of the thread. During relative rotation between the sleeve parts 86 and 61, and the lead screw 88, the balls roll in the continuous helicoidal passage formed by the helicaliy-shaped beveled portions 15 and I6 and their joining arched portions I8 and I9.

Considering the movement of one ball, as an example, relative rotation between sleeve parts and the screw causes the ball to travel along the thread 01 the screw for substantially one revolution. At the point where it reaches the end of the helically shaped portion of the groove it enters the arched portion, moves outwardly from the root to the crest of the screw to pass 68 about the entire periphery of the lead screw. Since the balls are constantly maintained, through the action of springs 85, in pressure engagement with the sides of the thread as well as the groove formed by the end portions 13 and I4,

parallel relative rotation between the lead screw and sleeve parts causes translatory movement between the leadscrew and'the sleeve parts as the balls move along the thread 83.

The spring pressure acting on the balls to engage them with the sides of the thread 83 eliminates, for all practical purposes, any back-lash or play in axial as well as radial-directions with respect. to the screw 68. In order to prevent'rotation of the carriage about the axis of screw 68, a depending arm 88 carries a guide roller 89 in engagement with the guide rail 9| that extends parallel to the lead screw 68. A flange 92 engages the opposite side of the guide rail 8| .L T 9,441,168: 4 i

which 'engacefthe threadof the lead screw. In,

this manner rthe'icarriag maybe supported on the leadscrewsvithoutfintroducing undue frlc-' tion; By (havingfpressure, continuously exerted r on the balls,';back lash between the lead screw and thenut 'isgeliminated. Since the lead screw f may carry practical'ly'the entire load supported by itsv carriage, it is unnecessary to have the usual supporting rails to support the carriage in devices of this type. The onlyadditional guidemember comprising ascrew rotatable about an axis, a car riage, translatable along said axis, a lever pivotally. supported on said carriage, a rotatable member carried by said lever'in' rolling contact with the thread or said-screw-ior translating said carrlage, and means-connected to said lever for ex- I erting pressure to maintain saidrotatable membet in engagement with the sides of said thread tol'reduce' play between said carriage and said screw,

6. sma hes r the character "described,

comp ising .a screw rotatable about an'axis, a'

" 2 carriage translatable along said axis, .a plurality oi rollers rotatable on said carriage for engaging screw for preventing -rotation oi the, not about a the axisoi. the screw. f

lash is eliminated through action oi pressure resiliency appliedto rotatable members coupling the carriage to'the lead screw.

Since many changes could be-made in the above construction andmany apparently widely diiferent embodiments of this invention could be made without departing from the scope thereof, it is intended that all 'matter'containedin the abovedescription' 'or shown inthe accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

What'is claimedis: I r

1. A mechanism-off the character described comprising -,a screw rotatable about an axis, a carriage translatable along said axis, and means for supporting", saidcarriage on said screw including 'a' rvtatable'; member engaging the thread of said screw andformiriga rolling contact therewith fortranslating said carriage upon turning of said screw',';sai'd me'ans additionally providing peripheral-- thread contacting elements.

2. A mechanism bf the character described" comprising ascrewrotatable, about :an axis, a

carriagetranslatable'alongsaid axis, means for supporting said carrlag on saidscrew including,

a rotatable member-engaging .the, thread of said the apparatus provide f a combined, anti iriction support andtranslat ing mechanismgforgmoving acarriage. Backrequired -isa rail1extending parallel .to the lead f1; .A mechanism.

thecrestoigthe' thread of said screw to support I i said- .carriagethereon, and amember connected,

to sfaidfcarrlage' for engaging the thread-oi said 1 screw itor translating said carriage upqrf turning of said crew 1 riage-translatable; along said, axis; a. plurality of V rollers rotatable oii saidfcarriage ior engagingthe crest'bt the thread'of. s'aid'screw to support said carriage, thereon, a member-carried by saidcarriage in'a manner such that rotationof said screw causes translation of said carriage, and re"- silient means exerting pressure to maintain said member; iii-engagement with the sides ofsa'id thread to reduce play between said carriage and said screw.

8. In-a mechanism of the character described,

I a translatable carriage comprising a sleeve adapted to surround a screw, a plurality of rollers rotatably supported on said sleeve for engaging the I 4 round a lead screw, a pluralityof rollers rotatable about axes on saidsleeve for engaging the crest ofthe thread of said screw, 9, rotatablemember carried by said carriage for engaging the sides oi" said thread and forming a rolling contact screw and forming-a rolling: contact therewith for'translating said carriage upon tuming of said screw, and resilient means exerting pressure to maintain said rotatable member-in engagement with thesides ofl'said thread to reduce play between saidcarriage and'said screw.

3. A mechanism of the character described comprising a screw member, a. nut member, said members being arranged for relative rotation about an axis and'relative translation along said axis, and at least two rotatable elements, one element being interposed betweensaidm'embers for. .v

causing relative translation fsai'd members upon relative rotationthereof and the other element being arranged for contact. with the crest of said screw member.

4. A mechanism about an axis and relative translationalong said axis, a rotatable element "carried by saidnut Q br thecharacter described comprisinga screw member, 'a nut member, said members being arranged for. relative rotation therewith, and resilient means exerting pressure to' :maintain; said member in engagement with the sides oi'said thread, said rollers and said member being arranged in a manner to restrain said sleeve'from movementradially-and axially of said screw. I

10. A.mechanism of the character described,

comprising "a screw rotatable about an axis, a

carriage translatable-along said axis and a pinrality of balls interposed between said screw and I saidcarriage in a manner such that rotation of said screw causestranslation of said carriage, and resilient. means for exerting pressure to maintain said balls in engagement with the sides of said thread to reduce play between said'car-z I riage and said. screw.

11. Amechanism of the character described, comprising a threaded screw, a sleeve surrounding saidscrew and formed with a helical groove having its ends joined by an arch, a plurality of balls engaging thethread of said screw and retained' by the grooved portion of said sleeve to form an anti-friction coupling for causing relative translation between said sleeve and said screw upon relative rotation thereof saidarch being arranged to permit movement ofsaid balls overthe-crest of said thread to provide a. continuous passage for said balls, and resilient means exerting pressure to maintain said balls in env of the-character described I comprisin a screw: mtatableabout an axis, a car-[ parts, and means including yielding connective devices for connecting said parts in a manner such that said end surfaces cooperate to form a continuous track for retaining a ball between the 1 thread of a screw and said sleeve parts,

13; In a mechanism of the character described, a, pair of sleeve parts having helically-shaped end surfaces connected by an arch extending outwardly from the center of said sleeveparts, and resilient means connecting. said parts in a manner such that said end surfaces cooperate to form a continuous track for retaining a ball between the thread of a screw and said sleeve parts and exert pressure to maintain said ball in engagement with the sides of the thread to reduce play between said sleeve and screw.

14. In a mechanism of the character described.

a first sleeve part having a heiically-shaped end surface connected by an arch extending outwardly from the center of said sleeve part, and a second sleeve part having a similarly-shaped helical end surface connected by an arch, and means including resilient elements for connecting said parts in a manner such that said end surfaces cooperate to form a continuous slightly yieldin track or ball race for holding balls between the thread of a screw and said sleeve parts.

- 15. In a mechanism of the character described, a first sleeve part having a helically-shaped end surface connected by an arch extending outwardly from the center of said sleeve part, a second sleeve part having a similarly-shaped helical end surface connected by an arch, and resilient means for connecting said parts in a manner such that said end surfaces cooperate to form a continuous track for holding balls between the thread of a screw and said sleeve parts and exert pressure to maintain said balls in engagement with the sides of said thread to reduce play between said sleeve parts and screw.

16. In a mechanism of the character described, the subcombination comprising two interiorly symmetricalball retaining members, said members being so arranged interiorly that balls placed therein may traverse a helical path, and

- symmetrically arranged means including resillent elements for holding said members flexibly together and for facilitating proper path definition of said moving balls. 7

CHARLES H. RICHARDSON.

REFERENCES CITED The foiiowing'references are of record in the file of this patent:

' UNITED STATES PATENTS Great Britain Sept. 24, 1940 

